Discovery of Small Peptides as Dual Inhibitors of IL-4 and IL-13 Signaling

Abstract Interleukin-4 (IL-4) and interleukin-13 (IL-13) signaling are central drivers of type 2 inflammation. While monoclonal antibodies targeting this pathway are clinically effective, their use is limited by high production cost, poor tissue penetration, increased risk of adverse effects, and parenteral administration requirement. Peptides offer advantages including structural tunability, favorable safety profiles, and improved tissue accessibility. Here, we employed an alternating phage display biopanning strategy to identify small peptides capable of dual modulation of IL-4 and IL-13 signaling. Sequential selection against IL-4 receptor α (IL-4Rα) and IL-13Rα1 enriched ligands with intrinsic dual-targeting capability. Lead peptide FMI-15 inhibited IL-4/IL-4Rα and IL-13/IL-13Rα1 interactions with IC50 values of 7.98 and 3.13 μM, respectively. In HEK-Blue reporter assays, FMI-15 suppressed IL-4- and IL-13-induced signaling with EC50 values of 25.1 and 31.6 μM, respectively. The peptide exhibited minimal cytotoxicity and moderate serum stability (t1/2 = 28.9 min). These findings establish alternating phage display as an effective strategy for identifying dual-targeting peptide modulators of cytokine signaling.